diff --git a/lib/pub_cache.dart b/lib/pub_cache.dart
index c9e622a..ccbadbc 100644
--- a/lib/pub_cache.dart
+++ b/lib/pub_cache.dart
@@ -10,19 +10,16 @@
 import 'package:pub_semver/pub_semver.dart';
 import 'package:yaml/yaml.dart' as yaml;
 
-// TODO: do things like get all the versions for a package?
-
 // TODO: get the latest version for a package?
 
 // TODO: get the latest non-dev version for a package?
 
-// TODO: get all the packages (id's only) in the pubcache
+// TODO: Scan for git packages.
 
 /**
- * TODO:
+ * A programattic API for reflecting on Pub's cache directory.
  */
 class PubCache {
-
   static Directory getSystemCacheLocation() {
     if (Platform.environment.containsKey('PUB_CACHE')) {
       return new Directory(Platform.environment['PUB_CACHE']);
@@ -52,10 +49,30 @@
     return dir.existsSync() ? dir.listSync() : [];
   }
 
+  /**
+   * Return applications that have been installed via `pub global activate`.
+   */
   List<Application> getGlobalApplications() => _applications;
 
+  /**
+   * Get all the packages and their versions that have been installed into the
+   * cache.
+   */
   List<PackageRef> getPackageRefs() => _packageRefs;
 
+  /**
+   * Return the list of package names (not versions) that are available in the
+   * cache.
+   */
+  List<String> getCachedPackages() =>
+      new Set.from(getPackageRefs().map((p) => p.name)).toList();
+
+  /**
+   * Return all available cached versions for a given package.
+   */
+  List<PackageRef> getAllPackageVersions(String packageName) =>
+      getPackageRefs().where((p) => p.name == packageName).toList();
+
   void _parse() {
     // Read the activated applications.
     _applications = [];
@@ -66,8 +83,6 @@
           (dir) => new Application._(this, dir)).toList();
     }
 
-    // TODO: Scan for git packages.
-
     // Scan hosted packages - just pub.dartlang.org for now.
     _packageRefs = [];
 
@@ -90,15 +105,21 @@
   final Directory _dir;
 
   List<PackageRef> _packageRefs;
-  Version _version;
 
   Application._(this._cache, this._dir);
 
   String get name => path.basename(_dir.path);
 
   Version get version {
-    if (_packageRefs == null) _parsePubspecLock();
-    return _version;
+    PackageRef ref = getDefiningPackageRef();
+    return ref == null ? null : ref.version;
+  }
+
+  PackageRef getDefiningPackageRef() {
+    for (PackageRef ref in getPackageRefs()) {
+      if (ref.name == name) return ref;
+    }
+    return null;
   }
 
   List<PackageRef> getPackageRefs() {
@@ -116,15 +137,6 @@
       Map m = packages[key];
       return new _AppPackageRef(_cache, m['source'], key, m['version']);
     }).toList();
-
-    String name = this.name;
-
-    for (PackageRef ref in _packageRefs) {
-      if (ref.name == name) {
-        _version = ref.version;
-        break;
-      }
-    }
   }
 }
 
diff --git a/test/pub_cache_test.dart b/test/pub_cache_test.dart
index 147ca06..a15ba4d 100644
--- a/test/pub_cache_test.dart
+++ b/test/pub_cache_test.dart
@@ -41,6 +41,16 @@
       PubCache cache = new PubCache();
       expect(cache.getPackageRefs(), isNotEmpty);
     });
+
+    test('getCachedPackages', () {
+      PubCache cache = new PubCache();
+      expect(cache.getCachedPackages(), isNotEmpty);
+    });
+
+    test('getAllPackageVersions', () {
+      PubCache cache = new PubCache();
+      expect(cache.getAllPackageVersions('path'), isNotEmpty);
+    });
   });
 
   group('Application', () {
@@ -60,6 +70,10 @@
       expect(app.version, isNotNull);
     });
 
+    test('getDefiningPackageRef', () {
+      expect(app.getDefiningPackageRef().name, app.name);
+    });
+
     test('getPackageRefs', () {
       expect(app.getPackageRefs(), isNotEmpty);
     });